boiling coolant

I was riding some really slow technical stuff yesterday, and when I stopped I noticed the coolant in my radiator was boiling and and it had drained some in the resivour which was also boiling still. Is this normal for extended slow riding?

I the bike is running rather lean, since my snorkel is removed and I have the GYTR insert and am on stock jets (my jets and fuel mixture screw is on backorder.) It cooled down when we got to some open trails, and still runs great. Could I have done any damage and is there anything extra I should look at when I check my valve clearances tomarrow? Thanks

Boiling is normal, especially with a lean bike. I'd bet nothing is damaged that wasn't there before and valves should be checked at break-in, and then once a season, more frequently if you're racing, unless you're experiencing hard starting, then check immediately...SC


Mine has boiled couple times on swamp when I got stuck or it was really really hard to get forward and engine was working hard. Pinging is another thing you will notice when engine gets too hot. When I did major maintenance on my bike I noticed nothing. Just take care that you have water there so it won't run dry. Thing that help cooling is change your coolant on warm seasons to battery water and redlines water wetter. Glygole transfers heat less out of engine than water.

Timo Mc

My '02 WR426 boiled on really slow ride with my 5-year-old last summer. I stopped right away, let it cool some, then went back out of the trail a little faster without a problem. Lower airflow through the rad cores = lower heat rejection. Given the right conditions, it's just a matter of time before she boils.

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